Update February 23, 2018 ― I've now settled on using a different method. I still use duct tape and a sharpie, but I've found a better, longer-lasting method of pinning a length of tape folder over (so no sticky left) with a push pin on each hive. This works better and is much longer-lasting in terms of tape not having to adhere to anything etc. Easily transferrable to another box, push pins stick in wood very well, and stands up to weather better. Cheap, easy, at the hive, no records to keep and carry around, and I can see at-a-glance without opening hive. Just bring a sharpie with you on trips to the apiary... I like the fine-point Milwaukie pens from Home Depot Works #perfect.

The past couple years, I've found Michael Palmer's advice about record keeping very handy. As you learn and grow more successful as a beekeeper, you may find yourself going well past three or four hives and you'll start forgetting important details such as:

Queenright?

Laying well?

How much did it weigh last?

Where did the queen come from?

What day did it swarm?

When did I create this split?

Need to feed?

Mite test results?

You could carry a notepad around with you, but you'll see how complicated that can be very quickly. And, there'll come that day you leave it at home or the dog eats it.